The Role in Ozone Phytotoxicity of the Evolution of Ethylene upon Induction of 1-Aminocydopropane-1-carboxylic Acid Synthase by Ozone Fumigation in Tomato Plants

The rate of evolution of ethylene by tomato plants was rapidlyincreased by O₃ fumigation. The time course of the increasein 1-aminocyclopropane-1-carboxylic acid (ACC) synthase activitywas the same as that in the rate of evolution of ethylene, suggestingthat ACC synthase activity might be a rate-limiting step inthe evolution of ethylene that is caused by O₃ fumigation. Therate of the O₃-induced evolution of ethylene was increased bythe application of ACC to tomato plants, suggesting the involvementof ACC oxidase in the O₃-induced evolution of ethylene. Treatmentof plants with tiron inhibited the evolution of ethane, butnot of ethylene. These results indicated that evolution of ethylenein O₃-treated tomato plants might result from enzymatic reactionscatalyzed by both ACC synthase and ACC oxidase, but not fromstimulation by O₃ of the peroxidation of lipids mediated byfree radicals. Pretreatment of leaves with aminoethoxyvinylglycine (AVG), aninhibitor of ACC synthase, significantly inhibited the evolutionof ethylene that was induced by O₃ and concomitantly reducedthe extent of O₃-induced visible damage to leaves. Treatmentwith 2,5-norbonadiene, an inhibitor of the action of ethylene,strongly reduced the extent of visible damage caused by O₃,even though it did not suppress the evloution of ethylene. Theseresults indicate that ethylene acts on certain metabolic processesto cause visible damage. (Received September 7, 1995; Accepted December 18, 1995)     

Induction and Repair of Damage to DNA in Cucumber Cotyledons Irradiated with UV-B

Photoinduced lesions in DNA, namely, cyclobutane pyrimidinedimers (CPDs) and pyrimidine-(6-4)-pyrimidone photoproducts[(6-4)photoproducts], in cucumber cotyledons that had been irradiatedwith naturally occurring levels of UV-B (290–320 nm) werequantitated by enzyme-linked immunosorbent assays with monoclonalantibodies specific to each type of photolesion. Induction ofthese photolesions was dependent on temperature and their extentwas reduced by simultaneous irradiation with white light. Thedark repair of both types of photolesion was undetectable. Light-dependentremoval of (6-4)photoproducts was very slow, with 50% removalin 4 h. By contrast, 50% of initial CPDs were removed within15 min. Both photorepair processes were dependent on the intensityof white light and were sensitive to temperature. These resultsindicate that high photolyase activity is present in cucumbercotyledons and that repair activities in cucumber cotyledonsare different from those reported in Arabidopsis, in which (6-4)photoproductsare photorepaired more rapidly than CPDs. (Received October 13, 1995; Accepted December 28, 1995)     

Biochemical systematics of Japanese fireflies of the subfamily Luciolinae and their flash communication systems

Japanese fireflies of the subfamily Luciolinae are biochemically analyzed using 13 allozymes, and the phylogenetic relationships obtained from this analysis are compared with their flash communication systems. As a result, the Japanese Luciolinae can be divided into three groups.Hotaria parvula andH. tsushimana together withLuciola yayeyamana andL. kuroiwae from the first group, and they use the same communication system.L. lateralis, Curtos okinawana, andC. costipennis make up the second group, and their communication systems are also the same.L. cruciata makes up the last one, and its communication system is different from the other fireflies of Luciolinae. Therefore, their taxonomical arrangement and communication systems are not congruent. However, the genetic similarity deduced by allozymic analysis of the members of the Japanese Luciolinae is highly consistent with their flash communication systems.     

An Integrated Map with Cosmid/PAC Contigs of a 4-Mb Down Syndrome Critical Region

The major phenotypic features of Down syndrome have been correlated with partial trisomies of chromosome 21, allowing us to define the candidate gene region to a 4-Mb segment on the 21q22.2 band. We present here a high-resolution physical map with megabase-sized cosmid/PAC contigs. This ordered clone library has provided unique material for the integration of a variety of mappable objects, including exons, cDNAs, restriction sites, etc. Furthermore, our results have exemplified a strategy for the completion of the chromosome 21 map to sequencing.     

Lithium chloride-tolerant character of the heterobasidiomycetous yeastRhodotorula glutinis

The heterobasidiomycetous yeastRhodotorula glutinis was able to grow in medium containing a high concentration of LiCl. This character ofR. glutinis was presumed to be attributable to its ability to incorporate [¹⁴C]-adenine and [¹⁴C]-leucine into nucleic acids and proteins, respectively, in the presence of LiCl. Intracellular levels of Li⁺ and Cl^– ions, production and accumulation of glycerol as an osmoregulator, and respiration in the LiCl-stressed condition were almost the same in the tolerant yeastR. glutinis and the sensitive yeastRhodosporidium sphaerocarpum.     

Transient expression of bile-duct-specific cytokeratin in fetal mouse hepatocytes

The differentiation of hepatocytes and biliary epithelial cells has been histochemically analyzed with anti-calf cytokeratin antiserum in the fetal mouse liver. Almost all young fetal hepatocytes transiently express bile-duct-specific cytokeratin; subsequently, the strong staining of the cytokeratin is confined to progenitor cells of intrahepatic biliary epithelial cells around portal veins. These results suggest that all fetal hepatocytes are bi-potent in terms of the differentiation of mature hepatocytes and intrahepatic bile-duct cells, and that the microenvironment around portal veins plays an important role in bile-duct differentiation. Large periportal hepatocytes continue to stain weakly for cytokeratin until 2 weeks after birth, although the number of positive hepatocytes decreases with development. The differentiation of bile ducts from periportal hepatocytes may continue for 2 weeks after birth.     

Phloretin as an Antagonist of Prostaglandin F2α Receptor in Cultured Rat Astrocytes

Abstract: The effect of phloretin on prostaglandin (PG) F_2α-induced phosphoinositide hydrolysis and elevation of intracellular Ca²⁺ concentration was examined in cultured rat astrocytes. Phloretin inhibited PGF_2α (1 μ M )-induced phosphoinositide hydrolysis in a concentration-dependent manner with an IC₅₀ value of 16 μ M . The inhibitory action of phloretin was specific for PGs. The addition of increasing concentrations of phloretin caused progressive shifts of the dose-response curves of PGF_2α to the right. In digitoninpermeabilized astrocytes, phloretin (100 μ M ) inhibited the stimulation induced by PGF_2α (1 μ M ) plus GTPγS (50 μ M ) without affecting that induced by GTPγS alone. PGF_2α at 1 μ M transiently increased astrocytic intracellular Ca²⁺ concentration in 39% of the cells tested. The response was completely blocked by 100 μ M phloretin and the calcium response recovered again after washing out phloretin. These results suggest that phloretin is an antagonist of PGF_2α receptor linked to phospholipase C in astrocytes.     

Ischemic changes in myocardial ionic contents of the isolated perfused rat hearts as studied by NMR

Using³¹P-,²³Na- and³⁹K-NMR, we assessed ischemic changes in high energy phosphates and ion contents of isolated perfused rat hearts continuously and systematically. To discriminate intra- and extracellular Na⁺, a shift reagent (Dy(TTHA)^3–) was used in²³Na-NMR study. In³⁹K-NMR study, the extracellular K⁺ signal was suppressed by inversion recovery pulse sequence in order to obtain intracellular K⁺ signal without using shift reagnets. During the early period of ischemia, increases in intracellular Na⁺ and inorganic phosphate (Pi) were observed in addition to the well-documented decreases in creatine phosphate and ATP and a fall of intracellular pH, suggesting an augmented operation of Na⁺–H⁺ exchange triggered by a fall of the intracellular pH resulted from breakdown of ATP. At around 15 min of ischemia, a second larger increase in intracellular Na⁺ and a decrease in intracellular K⁺ were observed in association with a second increase in Pi. This was accompnanied by an abrupt rise of the ventricular end-diastolic pressure. As there was a depletion of ATP at this time, the increase in intracellular Na⁺ and associated decrease in intracellular K⁺ may be explained by inhibition of the Na⁺–K⁺ ATPase due to the depletion of ATP. A longer observation with³¹P-NMR revealed a second phosphate peak (at lower magnetic field to ordinary Pi peak) which increased its intensity as ischemic time lengthened. The pH of this 2nd peak changed in parallel with the changes in pH of the bathing solution, indicating the appearance of a compartment whose hydrogen concentration is in equilibrium with that of the external compartment. Thus, the peak could be used as an index of irreversible membrane damage of the myocardium.     

The development of emotion regulation ability between the ages of 13 and 18 months in Japanese infants during the strange situation as a function of mothers' styles of emotion expression

The purposes of this study were two-fold. First, it compared Japanese infants' (N=129) abilities to regulate emotions at 13 months and 18 months of age, using the Strange Situation procedure. Second, it examined the relationship between the development of emotion regulation and the mother's emotion expression style as assessed by the Emotion Expression Style Questionnaire (EESQ). The total number of subjects who successfully completed all 8 episodes of the Strange Situation procedure increased significantly during the aging between 13 and 18 months of age, indicating that as a group these infants increased their ability to cope with stressful situations. However, infants who had mothers with negative emotion expression styles did not show greater capacity for emotion regulation at 18 months. These findings suggest that the development of emotion regulation is mediated by the mother's emotion expression style.     

Analysis of the thromboxane/prostacyclin balance in human urine by gas chromatography/selected ion monitoring: abnormalities in diabetics

We microanalyzed 2,3-dinor-6-keto-prostaglandin F_1α (2,3-dinor-6-keto-PGF_1α 1) and 11-dehydrothromboxane B₂ (11-dehydro-TXB₂, 2) in human urine. Samples containing a [²H₄]-analogue as an internal standard were extracted by chromatography using Sep Pak tC18 and silica gel. The compounds were then analysed by means of the lactone ring opening reaction and dimethylisopropylsilylation. The conversion of 1 to 1-methyl ester (ME)-propylamide (PA)-9,12,15-dimethylisopropylsilyl (DMIPS) ether derivative and of 2 to 1-ME-6-methoxime (MO)-9,12,15-tris-DMIPS ether derivative was followed by gas chromatography/selected ion monitoring (GC/SIM). Interfering substances from the urine matrix were eliminated during GC/SIM analysis using a DB-5 column. We were able to detect 1 (222–1031 pg/mg creatinine) and 2 (18–155 pg/mg creatinine) in human urine. Furthermore, the thromboxane/prostacyclin (IX/PGI) ratio in the urine of diabetics was higher than that of healthy volunteers. This method can be used to determine the TX/PGI balance in human urine.